Polymeric shells, including unsupported medical, surgical and other gloves, are typically made of latex. These polymeric shells are produced in an assembly line fashion by dipping a coagulant-coated former of desired shape into an aqueous latex emulsion, thereby gelling the latex and subsequently curing the gelled layer to form the polymeric shell. The aqueous latex emulsion may comprise additives, including viscosity modifiers, waxes, surfactants, stabilizers, cross-linking agents and the like, to produce a cured latex product having specific characteristics, such as thickness, tensile strength, tear and penetration resistance, flexibility; etc., in a controlled manner. Aqueous latexes of different compositions are known in the art, and they include natural rubber latexes, synthetic polyisoprenes, and other synthetic latexes, including neoprene, nitrile compositions, and the like. Typical examples of polymeric shells made from the aqueous dipping process are described in U.S. Pat. No. 3,268,647 to Hayes et al., which discloses the manufacture of rubber gloves.
Polymeric shells with a supported liner are known in the art and are typically used in applications that require a strong latex product commonly used in industrial environments, such as gloves, for protecting hands. A number of patents disclose coating the liner with a latex composition. For example, U.S. Pat. No. 2,083,684 to Burke discloses rubber-coated gloves and a method of making the same. U.S. Pat. Nos. 4,514,460, 4,515,851, 4,555,813, and 4,589,940 to Johnson disclose slip-resistant gloves and a method for their manufacture. U.S. Pat. No. 5,070,540 to Bettcher et al. discloses a protective garment. A metallic wire core and two fiber strand wrappings are coated by dipping in a nitrile rubber composition. U.S. Pat. No. 5,581,812 to Krocheski discloses a leak-proof textile glove. The inner surface of a cut-resistant textile layer is bonded to a leak-proof, petroleum-resistant, polymeric material, such as PVC, without an intervening adhesive layer, since the leak-proof polymeric material is applied to a liner placed on a former. U.S. Pat. No. 5,822,791 to Baris discloses a protective material and a method wherein a cut-resistant, protective layer is coated with an impervious elastomeric material. A typical process for producing these supported gloves includes the use of a liner, which is dressed over a former, optionally treated with a coagulant, and dipped into an aqueous latex emulsion to form a gelled latex layer over the liner, which is then cured. The penetration of the aqueous latex emulsion into the dressed liner results in ‘strike-through,’ or “penetration,” which creates an unsightly appearance of the supported product and makes the article more rigid and less flexible. A number of steps are taken to minimize ‘strike-through,’ including coagulant coating of the liner as a blocking agent, and increasing the viscosity of the aqueous latex emulsion to prevent the penetration of the aqueous emulsion into the liner; etc. The aqueous latex emulsion used may comprise several additives, such as stabilizers, foaming agents, cross-linking agents, waxes, and surfactants. The latex composition may be natural rubber, polyisoprene, neoprene, or nitrile rubber; etc. These supported polymeric shell products provide sufficient protection to the hands of the wearer. The dipping and drying of a glove former in a latex emulsion to form a glove is disclosed. However, the chemical resistance of the polymeric shell is generally inadequate due to poor coverage of the latex emulsion over the liner and may have holes in the latex layer where the fibers of the liner cross. A further and perhaps more serious consequence of coating over a knitted fabric is the possibility that the resultant polymeric film is compromised, resulting in a non-uniform thickness, which may compromise the chemical-resistant barrier of the film in parts or which may not be liquid-proof. This is due to the potential of surface fibers passing into or through the coating, hence providing an easier path for liquids to pass or permeate through the polymeric film. Foamed latex layers may have interconnected porosity, which also may provide decreased chemical resistance to the supported polymeric shell latex article.
U.S. Pat. No. 4,283,244 to Hashmi discloses a method of making fabric-lined articles. This method of making a lined elastomeric article comprises the steps of applying a coating of adhesive in a liquid state to an elastomeric article on a form, drying the adhesive on the article to form a pressure-sensitive adhesive coating, treating the adhesive coating with a lubricant, and thereafter applying a preformed lining over the article and the adhesive coating to connect adhesively the lining to the elastomeric article. The elastomeric article is a latex product produced by dipping a coagulant-treated former into an aqueous latex emulsion and drying and curing the elastomeric article on the former. The adhesive is 68096-01 resin supplied by Evans Adhesives of Columbus, Ohio, suspended in water. The elastomeric article on the former is dipped in the adhesive, dried to form a pressure-sensitive adhesive coating, lubricated, and dressed with a liner. The lined elastomeric article is removed from the former and turned inside-out. Unfortunately, the sweating action combined with body temperature results in the extraction or dissolution of the adhesive, producing an unpleasant skin feel. The adhesive also is soft, has low strength properties, and stays tacky even after drying.
U.S. Pat. No. 4,918,754 to Leatherman et al. discloses a flocked glove and a plastic sleeve member bonded thereto. A preformed, flock-lined, rubber-like glove has its cuff folded back to expose the flocked lining, is mounted in a rotating support, and is sprayed with a hot-melt adhesive on the flock-lined, folded cuff. The glove is telescoped onto a polyethylene sleeve, and the adhesive is melted by high frequency heating to bond the polyethylene sleeve with the cuff. The adhesive bonds the polyethylene sleeve to the cuff portion of the glove and does not bond the entire polymeric shell with a liner.
U.S. Pat. Nos. 5,599,895, 5,618,904, and 5,932,680 disclose moisture-curing polyurethane hot-melt adhesive. The hot-melt adhesive includes at least one polyurethane prepolymer of at least one polyisocyanate, toluene diisocyanate, and/or MDI, at least one polyalkylene glycol, at least one polyester glycol, and optional additives, such as a stabilizer, particularly toluenesulfonyl isocyanate.
U.S. Pat. Nos. 6,543,059 and 6,596,345 to Szczesuil et al. disclose a protective glove and a method for making same. This protective glove for a human hand includes an inner glove of polyester, non-woven, needle-punched material and a melt-sprayed polyurethane coating. This non-woven needle punched material has no mechanical integrity, unlike a woven or knitted fabric, and the hot-melt-sprayed polyurethane adhesive holds the configuration together, forming a glove. The melt-sprayed glove is heated to a temperature of 300 to 325° F. to allow the remelted polyurethane to penetrate the inner glove to a depth short of penetrating to the inner surface of the inner glove. The polyurethane coating on the outer surface of the inner glove cures in approximately 24 hours by reaction with ambient moisture. The inner glove is further coated with a rubberized material to produce an inner glove held together by the rubber, which is then cut into pieces and sewn to form a glove with internal sewn seams. Such a glove is not liquid-impervious, since these sewn seams are not bonded and leak and, therefore, not chemically resistant. The protective glove is said to protect from puncture.
U.S. Pat. No. 6,539,552 to Yoshida discloses a flexible waterproof glove. This waterproof glove is formed of a flexible inner glove body of a base fabric that is thermally bonded with a low-melting, thermal plastic resin film and a flexible outer glove body of the same fabric. The thermal bonding of the inner glove with the outer glove is accomplished by heating the glove to melt the low-melting, thermal plastic resin film, which has a lower melting point than that of the base fabric. The melted thermal plastic resin film results in a watertight glove. In one embodiment, the thumb portion of the glove is manufactured separately and bonded to the rest of the glove to provide improved thumb movement. The molten and solidified polymer thermally bonded to the inner and outer glove body results in a watertight glove. The overall rigidity and resistance to movement of the glove is addressed by the separate attachment of the thumb component to the glove. There is no latex or polymeric shell in this glove. Thus, this glove has no stretch characteristics resembling those that are commonly available in a latex-based glove product.
Therefore, there is a strong need in the art for a supported, chemically resistant, polymeric shell, latex article that effectively manages moisture, such as sweat, and exposure to body temperature. The liner provides stretch resistance, a comfortable feel, moisture (e.g., sweat) management, and cut-resistance as desired, while the polymeric shell provides chemical resistance. There is also a need in the art for a manufacturing process that produces a supported, polymeric shell, latex article in a production environment. A more efficient method for adhering a liner to a polymeric shell is needed. Additionally, a method is needed that substantially minimizes, and preferably eliminates, strike-through, i.e., penetration of a latex composition into the liner. Further, a method is needed that will insure the physical integrity of the polymeric shell, i.e., no thin or weak areas or holes, thus providing a sound liquid-proof barrier. It is an object of the present invention to provide such a method. It is another object of the present invention to provide an article comprising a polymeric shell, an adhesive, and a liner, and having physical integrity taking advantage of the unique properties of the liner and that of a chemically resistant liquid-proof polymeric shell. These and other objects and advantages, as well as additional inventive features, will be apparent from the detailed description provided herein.